US3294075A

US3294075A - Injection system for internal combustion engines

Info

Publication number: US3294075A
Application number: US402162A
Authority: US
Inventors: Gratzmuller Jean Louis
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-09-25
Filing date: 1964-10-07
Publication date: 1966-12-27
Anticipated expiration: 1983-12-27
Also published as: BE653095A; AT265747B; GB1080359A; CH512672A; DK117327B; FR86373E; FR1380547A; ES304315A1

Description

1966 J. GRATZMULLER 3,

INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Oct. 7, 1964 v 4 Sheets-Sheet 1 FIGS 1966 J. 1.. GRATZMULLER 3,294,075

INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Oct. 7, 1964 4 Sheets-Sheet 2 FIG.4

Dec. 27, 1966 J. GRATZMULLER 3,294,075

' INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Oct. '7, 1964 4 Sheets-Sheet 5 F IG.6

wet, 11956 J. L. GRATZMULLER 32 INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Oct. 7, 1964 4 Sheets-Sheet United States Patent 8 Claims. C1. 123-439 The present invention relates to a method and a device for injecting a combustible liquid into an internal combustion engine, with automatic regulation of the volume injected in relation to the engine speed.

Heretofore, systems of injecting combustible liquid into engines, especially into Diesel engines, included a high pressure proportioning pump in association with a regulator. In the best-known type of pump, the piston exhibits a helicoidal ridged member which uncovers the suction orifice to a greater or lesser degree according to the angular position of the said piston and this angular position can be altered by means of a control of the rack type or the like. The regulator acts on this rack to restore, in the event of speed variation of the engine, the quantity of fuel injected to the quantity appropriate to the selected and predetermined speed. These systems, which are known as injection-regulator pumps are expensive appliances and their price is proportionately high, the smaller the power of the engine, thus hindering the development of small-power Diesel engines.

The present invention has for an object to provide an injection system in which regulation is automatically ensured by a volumetric auto-regulator pump driven by the engine. This pump progressively decreases the volume injected in relation to speed as soon as the engine speed exceeds a predetermined value, which regulates the running of the engine, the range of speed comprised between this predetermined speed and the speed at which all injection ceases being capable of being very narrow, if desired, so as to bring about very sensitive regulation. In addition, an auto-regulator pump in accordance with the invention is of much less costly construction than the pumps hitherto known.

In its simplest form, the invention consists in limiting the suction flow of the pump by means of an invariable calibrated orifice so that, for an engine speed higher than a predetermined speed, i.e. for a duration of the cycle of suction of the pump less than the predetermined duration of this cycle corresponding to the said predetermined speed, the quantity of fuel introduced into the pump is less than the quantity introduced at the said predetermined speed; also the quantity of fuel forced back at each injection into the engine decreases as soon as the engine exceeds the desired running speed, which tends automatically to bring the engine back to this running speed. In accordance with this simple form, regulation is not very sensitive since the volume injected varies to any extent only in inverse proportion to the speed, and since injection is never completely shut off.

In accordance with one preferred method of carrying out the invention, complete regulation can be automatically obtained, i.e., going from full injection to nil injection, for a speed range of determined extent beyond the predetermined running speed.

The method consists in sucking into the cylinder of a pump driven by the engine a quantity of fuel very much greater than that which is to be injected into the engine, in slowing down this suction, and in forcing back towards the engine, fuel under pressure during only a first reduced proportion of the pumps forcing back cycle, the remainder of this cycle determining the forcing back of the excess fuel to a low pressure zone.

3,2Q4fitl75 Patented Dec. 27, 1966 In accordance with this method, if, for the predeter mined speed N1 of the engine, the pump sucks in a volume V of fuel and forces back to the injector -a proportion v, corresponding, for example to A of V, the amount of suction [will be slowed down or limited so that, for a speed N2 N1 (for example, N2 equal 1.1 N1) of the engine, the pump now sucks in only a volume equal to V-v, and so that also, in the reduced portion of its cycle or its active portion where the pump is forcing back to the injector, this pump will have nothing to force back, i.e., the injection will be nil and there will have been obtained complete automatic regulation for a range of determined speed comprised between and of the speed N1.

In accordance with the preferred method of carrying out the method, the pumps forcing back cycle is divided into three parts, a first in which forcing back is effected to the low pressure zone, a second intermediate part of reduced value in which forcing back is made to the injector, and a third part in which forcing back is again effected to the low pressure zone, which has the advantage of locating the active portion of the force stroke of the pumps piston in the middle Zone of this stroke where the piston has a high speed and quickly builds up the high pressure necessary for injection into the Diesel engine.

In accordance lWllIh the method, the suction output of the pump is slowed down so that, at the predetermined speed N1, the cylinder of the pump is not completely full, the predetermined speed N1 corresponding to the introduction into the pumps cylinder of a volume of fuel equivalent to the volume formed by the displacement of the piston in the aforementioned second and third portions of the stroke.

The invention also has for an object to provide an auto-regulation system of injection which comprises a piston pump driven by the engine to be supplied and of which the suction orifice is joined to a reservoir of liquid fuel while the force valve is joined to the injector of a cylinder of the said engine, characterised by the fact that the cylinder of the said pump is very much greater than the volume of fuel to be conveyed into the cylinder of the engine at each injection, by the fact that the suction piping of the said pump is provided with an opening of calibrated section which limits the suction output, and by the fact that means are provided to put the pump cylinder in communication with a low pressure zone during the greater part of the pumps forcing cycle, the said means of communication being interrupted to permit forcing of fuel towards the injector, at least during a reduced intermediate portion of this cycle.

In an injection system in accordance with the invention, a pressure very much lower than atmospheric pressure prevails in the pump chamber during a large part of the phases of this pumps working, and for this reason, in order to prevent any introduction of air, there is preferably used a pump made tight by means of a liquid ring of the kind described in my United States Patent No. 3,073,255.

In accordance with one form of carrying out the invention, the auto-regulator pump which ensures injection for each cylinder of the engine is a single-piston pump, but, in the preferred forms of carrying out the invention, there is used a pump incorporating two pistons mechanically or hydraulically associated, these two pistons having different functions. The pump may thus incorporate a small-diameter piston the function of which is to suck from the source of supply and to force towards the injector the proportion v of fuel. The pump may also incorporate a large-diameter piston the function of which is to suck in and force back towards the low pressure zone the volume of fuel very much greater than the said proportion v referred to heretofore.

The coupling-up of the two stages of a two-piston pump of this kind may be effected either in the form of a low-pressure stage associated with a high-pressure stage, or in the form of two stages of different cylinders arranged in parallel.

Embodiments of the invention will be described by way of example only with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic view in section of an autoregulator injection pump in accordance with the invention.

FIG. 2 illustrates one form of control cam for a valve which can be used in a pump in accordance with the invention.

FIG. 3 is a partial view of a pump incorporating a valve which is to control, as a single valve, suction and forcing back towards the low pressure zone.

FIG. 4 illustrates in section a variation of the pump in which the piston of the pump serves as a distributor valve.

FIG. 5 is a partial view of the suction circuit of the pump in which there is provided a system for slowing down the engine.

FIG. 6 is a view in longitudinal section of a two-piston injection pump incorporating a low pressure stage and a high pressure stage.

FIG. 7 is a sectional view of another method of carrying out the invention in which the two pump pistons work in parallel.

FIG. 8 illustrates the profile of the cams of the pump in FIG. 7.

FIG. 9 is a variation of FIG. 7 in which the smalldiameter piston travels actually inside the large-diameter piston.

Referring to FIG. 1, the injection pump comprises a cylinder 2 in which travels a piston 4 actuated by a to and-fro movement from some transmission system driven by the engine to be supplied, for example, by a rod 6 attached to a crank 8 the shaft 26 of which is connected to the engine haft. The cylinder 2 is provided with a suction orifice 10, with an orifice 12 for forcing back fuel to the injector, and with an orifice 14 for forcing back fuel to a low-pressure zone or tank. The orifice is connected, by way of a suction valve 16, to a fuel reservoir 18, while the orifice 12 is connected to the injector 13, by Way of a force valve 20, the ball of which is kept on its seat by a spring 22. As is usual, the cylinder 2 is mounted on a crank-case 24 carrying the pedestals of the shaft 26 of the crank 8.

In accordance with the invention, the cylinder of the pump is several times greater, e.g. 3 to 10 times, than the volume of fuel which is to be conveyed into the cylinder of the engine 17 at each injection. In addition, the suction piping is provided with a calibrated jet 28 which limits and slows down the throughput of fuel on being sucked in.

Finally, the orifice 14 is provided with a controlled valve putting the pump chamber into communication with the tank during the extreme portion III of the forcing stroke of the piston (and, if necessary the portion I of thi stroke) While during the reduced intermediate portion II of this stroke forcing and also during the suction stroke, this communication is not made.

In the forms of carrying out the invention to be described later, opening and closing of this communication are produced by the piston itself which covers and uncovers a suitable orifice, but any type of valve control may be used, for example, a cam 32 driven directly by rotation of the shaft 26 or through a train of gears of ratio 1/1, 34-36, this cam working in conjunction with a rod 38 arranged to raise the ball 40 of the valve 30 against a spring 42.

The cam incorporates a projection 44 which causes opening of the ball 40 in the portion 111 of the forcing stroke of the piston and, if necessary, a second projection (not shown in FIG. 1) which causes opening of the ball 40 in the portion I of the forcing stroke.

The piston 4 incorporates a neck 46 which is at all times in communication with an orifice 48 arranged in the cylinder and connected by a pipe 50 with the fuel reservoir 18, so as to form round about the piston an annular liquid joint preventing any admission of air, as described in the patent and certificate of addition aforementioned. The working of the injection system in accordance with the invention is as follows: the section of the calibrated suction opening 28 is selected so that, at the predetermined engine speed N1, the volume V of fuel sucked in at each complete suction stroke of the piston is equal to the volume formed by the displacement of the piston in the zones II and III of its previously-defined stroke, i.e. the volume V is less than the pump cylinder.

At bottom dead centre of the piston, the cylinder of the pump is thus not under pressure. The first portion I of the forcing stroke serves only to restore the pressure in the cylinder to a value in the region of atmospheric pressure and above all to give great speed of movement to the piston. In the zone II of its forcing stroke, the piston causes the pressure of the fuel to rise to the value necessary for injection, and injects into the engine a volume v of fuel corresponding to the proportion necessary in each cycle in the fixed running of the engine. Then the cam projection 44 opens the valve 30; the force valve 20 leading to the ball of the injector 13 falls down, which interrupts injection while the volume of fuel in excess, which corresponds to the volume formed by the piston in the zone III is forced back towards the tank through the pipe 52 (which preferably returns to the reservoir 18). For the speed N1 of the engine, therefore, each cylinder receives a constant proportion v of fuel.

If the engine speed increases, the suction time of the pump is further reduced and only a volume V' V penetrates into the cylinder of the pump, if, of course, when the piston reaches the zone II during the force stroke, atmospheric pressure has not yet been restored in the cylinder. The piston thus makes use of a portion of the zone II of its stroke first of all to restore this pressure and does not force towards the injector at injection pressure except during a portion of this zone, i.e. the proportion forced towards the injector in this case is smaller than the previous proportion v and the engine slows down.

The volume introduced into the pump being inversely proportional to the speed -N of the engine, it is seen that a nil injection is attained for a speed N2 such that:

N2N1 e ualsl e uals volume of zone II N2 q V q volume of zones II and III If then the active part II of the force stroke is I/Il of the force zones II and III, the injection will be nil for a speed higher than N1 by 10%.

In accordance with the method of performing the invention, just described, there would be, inversely, an increase in the quantity of fuel injected if the engine slows down to below the speed N1, the maximum quantity injected corresponding to the volume of the zones I and II. This possibility arises only at starting or in the case of overload of the engine and this injection which exceeds the normal proportion may give rise to disadvantages for the long life of the engine. Also, for certain applications, it is of advantage for the injection to remain constant for all speeds lower than, or equal to, the speed N1 (which eliminates all risk of overloading the engine) and for regulation to commence only beyond this speed N1. This result may be obtained, in the method of carrying out the invention of FIG. 1, if the valve 30 is controlled so that it is also opened in the zone I of the forcing stroke. In this case, use can be made of a cam 32' (FIG. 2) incorporating a second projection 44' so that forcing back towards the injector cannot take place except in the inter= mediate zone II where the piston forms the selected volume v.

In accordance with the method of performing the invention partly illustrated in FIG. 3, the suction valve 16 and the valve 36 for forcing towards the low pressure zone can be combined in a single valve 33 which is controlled, inserted betwen an orifice 16' of the cylinder 2 and the reservoir 18. The calibrated jet 23 is then arranged at any point of the piping connecting the reservoir to the orifice It). The ball 35 of the valve 33 is then controlled, against a spring 39, by a cam 37 arranged in such a way that this valve closes only during the active portion II of the force stroke of the piston 4. During the remainder of the force stroke, the excess fuel is returned to the reservoir 18 to be again introduced into the cylinder of the pump in the following suction stroke (part IV of the cam 37). This solution has the advantage of eliminating one of the valves and of simplifying the problem of the times of opening of the valves. It may be desirable, at the moment of starting from cold, to be able to flood the engine, i.e., to be able to inject into it a proportion of fuel very much greater than the normal proportion v corresponding to the volume formed by the displacement of the piston in the zone II. In order to obtain this result, there can be temporarily allowed the forcing back to the injector of all or part of the volume of fuel contained in the zone III of the cylinder, instead of forcing it towards the area of low pressure. It is suflicient to arrange on the pipe 52 (FIG. 1) a hand-controlled valve (not shown) the temporary opening of which, at the moment of starting up, cancels out the opening controlled by the valve 30 (FIG. 1) or 33 (FIG. 3).

In order to interrupt injection completely, when it is desired to stop the engine, it is sufficient to prevent the valve 30 (FIG. 1) or 33 (FIG. 3) from re-closing, for example by means of a fork 41 or similar means controlled manually whioh can be brought to bear on a shoulder 43 fixed to the control rod 38 of the valve.

In FIG. 4 there has been shown a preferred form of carrying out the invention in which the piston is attached to the driving shaft 26 by an eccentric 54 and in which the putting of the cylinder 2 of the pump into communication with the low pressure zone (comprised by the reservoir 18) is effected, in zones I and II of the forcing stroke, by the piston 4 itself which covers or uncovers the suction orifice lit.

The piston 4 incorporates, as in the previous case, a neck 46 which forms a liquid sealing ring and it further incorporates a neck 56 leaving only a piston head 58 of small depth which can cover or uncover the suction orifice 10.

Communication is established between the annular zone formed by the neck 56 and the chamber 60 of the pump, for example, by means of double drilling 62, axial and radial, in the piston head or by channels made in the cylinder.

The jet 23 is gauged in such a way that, at the end of the suction stroke of the piston 41- (position shown in FIG. 4), and at the engine speed N1, the volume V of fuel introduced into the pump cylinder is equal to the volume formed by the displacement of the piston in the zones II and III. The zone I of the forcing stroke is, as in the preceding case, dead travel, its aim being to speed up the piston 4 and to restore atmospheric pressure in the chamber 60. When the piston head reaches the bottom of the zone II of the forcing towards the injector, the shoulder 53 of the piston covers the suction orifice so that the chamber 60 (as well as the volume of the annular neck 56) form a closed space in which pressure rises until it raises the ball of the force valve 20 to the injector. The proportion v of fuel is thus injected under pressure while there takes place all the part II of the forcing stroke in which the suction orifice is closed. As soon as the lower edge of the shoulder 58 uncovers the orifice 10, communication is established, by the channels 62 and the neck 56, between the chamber 60 and the fuel reservoir 18 at low pressure to which the excess fuel contained in the chamber 60 is forced back during the course of part II of the forcing stroke of the piston.

If the engine speed increases, the volume of fuel introduced into the pump becomes less than the volume V, as formerly, as a result of the slowing down of the throughput by the jet 28, so that the volume of fuel forced back towards the injector in the active part II of the stroke also diminishes, but in a much greater proportion, which brings the engine back to its predetermined speed N1. In accordance with this method of carrying out the invention, injection remains constant up to the speed N1 and then decreases above this speed until being cut out for a speed N2, so that:

N2-Nl l e uals stroke II N1 V q stroke II uts III There can be arranged on the piping 64 connecting the reservoir 18 to the cylinder 2 of the pump a device for regulating the throughput, e.g., a needle valve 66 (FIG. 5) with, parallel to the whole of the needle 66 and the jet 28, a by-pass pipe 68 provided with a jet 70 finer than the jet 28, which serves as a slow running jet. In normal running at the speed N1, the needle 66 is open so that the suction throughput of the pump is limited by the two

jets

28 and 70 in parallel. If the needle 66 is closed, all flow of fuel through the jet 28 is stopped and regulation of suction is effected solely by the fine jet 70 gauged for slow running of the engine, for example, at the slow speed n1.

For the intermediate positions between full opening and complete closure of the needle 66, there will be obtained all engine speeds between N1 and n1, With automatic regulation of injection at each position of the needle.

In the methods of carrying out the invention just described, in which the pump incorporates only a single piston per injector to be supplied, this single piston must have a high stroke/bore ratio, in the case where a large V/v ratio is chosen (e.g. of the order of 10) for the purpose of going from full injection to injection ml for a relatively slight increase in speed (e.g. about 10%).

This high stroke/ bore ratio may make the manufacture of the pump a delicate matter especially when the injection pressures commonly used are very high.

The double piston pumps which are to be described hereafter allow stroke/bore ratios to be kept small at least in the parts subject to high pressures, which greatly simplifies manufacture.

The first stage of the pump illustrated in FIG. 6 is similar to the pump illustrated in FIG. 4, i.e. it incorporates a piston 74- which slides in a cylinder 2 and which is driven, from the shaft 26, by an eccentric 76. This piston incorporates a head 58 of height equal to the useful stroke II of the piston which is followed by a neck 56 communicating, by means of a double drilling 62 at right angles with the pump chamber 60. The fuel arrives from the reservoir 18 at the chamber 60 through piping 64 incorporating a gauged throttle 28. The piston is provided with a second neck 46, of a height equal to the stroke of the piston 74, forming a liquid sealing ring which is supplied with fuel (or with oil) through a drilling 48 made in the cylinder 2.

The working of this stage of the pump is identical with that of the pump illustrated in FIG. 4, except that the fuel forced back by the piston 74 during the course of the active phase II of its force stroke is not sent into the injector, but is utilised to displace a piston receiver 76' which slides in a cylinder 2', the said cylinder being with advantage formed by the upper part of the cylinder 2.

Above the first pump body there is mounted, so that it is liquid-tight, a second pump body 78 in which is drilled a bore 80 to receive a small diameter high-pressure piston 82. The chamber 84 of this second pump body is in communication, on the one hand with the fuel reservoir 18,

equals through a suction valve 86, kept closed by a light spring 88 and, on the other hand, with the injector (not shown) by a force valve 20 kept closed by a spring 22 balanced by the injection pressure. The whole apparatus just described constitutes the second stage or the high pressure stage of the pump.

The high-pressure piston 82 can be made one with the piston receiver 76', but to facilitate alignment of the two stages, connection between these two pistons can be effected by a ball-valve 90, the two pistons being kept towards their bottom point by a spring 92, which bottom point is determined by the coming to rest of a shoulder 94 of the piston 76' against the upper part of the cylinder 2'.

The working of the pump is as follows, when the engine which it supplies is rotating at the desired speed N1.

During the whole of its suction stroke, which lasts for a time 11, a function of N1, the piston 74 sucks in, through the jet 28, a volume of fuel V equal to the volume formed by the displacement of the piston over parts III and II of its stroke (this regulation of the volume V being obtained by a suitable choice of the calibre of the jet 28).

At bottom dead centre of the piston 74, the position shown in FIG. 6, the fuel contained in the chamber 60 is then not under pressure (all leakage being prevented by the liquid sealing ring 46) and the first part I of the up-stroke of the piston (between the bottom dead centre and the level of the jet 28) serves only to restore atmospheric pressure in the chamber 60 and to set at speed the piston 74. At this moment, the shoulder 58 of the head of the piston 74 reaches the point of covering the fuel orifice 28, which causes the chamber 60 to be closed during the whole of part II of the pistons stroke and the volume enclosed in this chamber to serve as intermediate fluid to push back the piston receiver 76 by a length equal to the height of the shoulder 58. The piston 82 is thus pushed back over the same length and, as the high-pressure chamber 84 had been previously filled with fuel on the descent of the piston 82 under the effect of the spring 92, a volume of fuel v equal to hxs (h being the height of the shoulder 58 and s being the surface of the small piston 82), which is equal to the proportion of fuel at full injection, is forced back through the flap 20 towards the injector.

It will be understood that, if the ratio between the surfaces of the piston 74 and of the piston 82 is large, e.g., of the order of 10 in the figure, the pressure in the first stage of the pump will be, for example, 10 times less than the injection pressure, which again means that the auto-regulator part of the pump works only at a relatively slight pressure. From this it results that problems of liquid-tightness are much more easily solved and that the life of the pump is lengthened. In addition, for the first stage of the pump, there can be selected a comparatively small stroke/bore ratio (since it is the linear displacements of the piston 74 which come into play and not the volumes formed by these displacements) which makes manufacture easier and more economical.

After the injection phase just described, the piston 74 effects part III of its up-stroke, i.e. the neck 56 comes level with the jet 28 and the chamber 60 is put into communication with a low-pressure zone (the reservoir 18) through the channels 62, the neck 56, the jet 28 and the piping 64. The pressure again falls in the chamber 60, the spring 92 makes the piston 82 descend again, also the piston receiver 76. From this it results that the force valve 20 towards the injector re-closes and a further proportion v of fuel is sacked into the chamber 84 through the suction valve 86. The fuel contained in the chamber 60 is forced back by the piston 74 towards the low pressure piping 64 until the piston 74 reaches its top dead centre and a new cycle begins all over again.

When the speed of the engine exceeds the prescribed speed N1, the duration of the suction stroke of the piston 74 becomes t2 t1, and, as a result of the slowing down brought about by the jet 28, the volume of fuel introduced during this time of short duration into the chamber 60 is less than the previous volume V. From this it results that the piston 74, during its up-stroke, does not restore atmospheric pressure in the chamber 60 except beyond the level of the jet 28 and that the useful force phase is shorter than previously. The stroke of the piston receiver 76', and, consequently of the piston 82 is then less than the previous stroke 11, so that the proportion of fuel forced by the piston 82 towards the injector is less than the previous proportion and the engine slows down until reaching the prescribed speed N1. In the method of carrying out the invention illustrated, the injection is nil for an increase in speed of about 10%, which brings about very sensitive regulation.

In FIG. 6 there has been shown a system of piping 96 which puts the chamber 98 mounted on top of the piston receiver 76 in communication with low pressure, e.g., the reservoir 18. This piping 96 has the sole purpose of recovering any possible leakages round about the pistons 82 and 76'.

It will be seen from the foregoing that the fluid working in the first stage of the pump serves only as intermediate fiuid and that it is not essential to use the fuel itself in this stage. Thus use could be made of oil which would also pack the liquid sealing ring 46. In addition, the cylinder 2 of the piston 74 and the cylinder 2' of the piston receiver are not necessarily coaxial and of the same diameter; they can be arranged side by side or even at right angles, so as to reduce the total height of the pump, communication between the two cylinders being effected by suitable piping.

In the method of carrying out the invention illustrated in FIG. 7, there is used a two-piston pump with pistons 74 and 82' of which the two chambers 60' and 84 are connected in parallel by a system of piping 100 and are in communication with the piping 64 for the arrival of fuel (through a gauged orifice 28) as well as with the force piping 102 towards the injector (through the force valve 20).

In accordance with the method of construction shown, the large-diameter cylinder 102', in which slides the piston 74', and the small-diameter cylinder 80 in which slides the piston 82' are bored out side by side in the one pump body 104 which is enveloped by a block 106 closing the cylinder heads, these two elements being assembled one against the other in a liquid-tight manner by means of bolts 108 and joints 110. The outside lateral surface of the pump body 104 is hollowed by a neck 112 which communicates with the fuel admission 64 bored in the block 106 and also with the jet 28 and the pipes 48-48 which supply respectively the liquid sealing rings 46-46, of the two pistons 74' and 82'. Of course, on one or both of the pistons there can be provided other liquid sealing rings, especially liquid rings supplied by oil. The upper part of the piston 82 is pierced by a channel 62' and is hollowed by a neck 56' so as to play the same role of sealing, with regard to the jet 28, as the piston 74 in the preceding method of carrying out the invention.

The piston 74' is actuated, against a return spring 114, being supported, on one hand against the pump body and on the other hand against a shoulder 116 of the piston, by a cam 118 which works in conjunction with a roller 120 mounted at the foot of the piston.

Similarly the piston 82' is actuated, against a return spring 122, by a cam 124 acting in concert with a roller 126 mounted at the foot of a push rod 128. This push rod 128 slides in a hole drilled in the pump body 104 and pushes the piston 8-2, by way of a ball 130. The two

cams

118 and 124 are carried on a common cam shaft 132 but the profile of the two cams is different, since, as will be seen from what follows, the movement of the two pistons is not synchronized. The volume formed by the displacement of the small piston 82 in the intermediate zone of its force stroke (i.e. in the zone where the upper shoulder of this piston covers the jet 28, zone 11 in the preceding figure) is equal to the volume of the proportion of fuel injected at full injection and the part of the large piston 74 consists simply in sucking in and forcing out the larger part of the volume V of fuel (variable in proportion to the speed) which serves to effect regulation due to the presence of the jet 28. If the two pistons have strokes which are substantially equal, there can be given to the piston 74' a diameter three or four times greater than that of the piston 82 if it is desired that injection should be nil for a speed about 10% higher than the selected speed. During the first part of the pumps force cycle, the large piston is stationary at the bottom point while the small piston ascends under the effect of its cam, As soon as the top of the small piston covers the jet 28, the volume made up by the chambers 60', 84' and by the piping 100 is completely closed so that the pressure lifts the ball 22 of the force valve 20 and the proportion of fuel v is forced back at the desired pressure towards the piping 102 and the injector. At the end of injection, the neck 56' of the piston 82' comes level with the jet 28, which puts the volume 60'84'-100 at low pressure and caused the ball 22 to fall back again. The piston 74' can then begin its forcing stroke and the two pistons, until reaching their top dead centre, drive towards the low pressure zone, e.g., towards the reservoir connected to the pipe 64, the excess volume of fuel contained in the pump body.

In the pumps suction cycle, the two pistons, returned by their springs, descend at the same time, and it is seen that, if the speed of the camshaft 132 exceeds the selected speed and if in consequence the duration of the suction cycle is less than the normal duration, the volume of fuel introduced into the pump will be less than the normal volume, so that, at the following forcing cycle, the small piston will only begin to force effectively towards the injector a certain time after the closing of the jet 28-. In other words it may be said that the function of the large piston is to create, with its suction, a vacuum, greater or lesser, according to the speed, in the pump chamber.

In FIG. 8 are illustrated by way of example the profiles formed on the two

cams

118 and 124, the bottom dead centre of origin being marked and the zone of injection being marked II on the profile of the cam 124. Numerous other cam profiles could, of course, be used.

The method of carrying out the invention illustrated in FIG. 9 is a variation of FIG. 7 in which the small piston 82", instead of sliding in a cylinder formed in the pump body, slides in a bore 134drilled in the large piston 74 itself. The compression chamber 136 is thus common to the two stages of the pump.

Working is absolutely identical with that previously described, but it will be seen that the jet 28, which is covered and uncovered by the small piston, is carried by the large piston, i.e., this moving jet has to be supplied with fuel through pipes and sliding joints such as 64-112- 138-140-142.

Of course, the throttled portion 28' itself can be located at any point in this piping, e.g., on 138 or 1452, so as to open into the interior of the cylinder 134, an orifice being provided which can be covered or uncovered by the small piston 82". 4

The small piston is actuated, as in the preceding case, by a push rod 128 against a return spring 122, but this push rod incorporates a shoulder 144 which, after a certain portion of the force stroke, begins to work in conjunction with the foot 146 of the large piston 74" so that, in the last part of the forcing cycle, the two pistons move in unison. The push rod 128' can be actuated by a cam, by an eccentric or even by a rocker arm 148 suitably controlled.

In the case where the push rod 128 itself, or else the rocker arm 148, is actuated by a cam, the profile of this latter can be selected so as to bring about a slowing down in the speed of the push rod, and consequently of the small piston, at the moment when the shoulder 144 comes into contact with the foot 146 of the large piston, so that the coupling of the two pistons is effected without jarring.

In the foregoing there have been described auto-regulator pumps supplying a single injector, for a singlecylinder engine, but it is to be understood, of course, that several identical pumps can be associated to supply the injectors of a multi-cylinder engine with fuel.

In accordance with another form of carrying out the invention, the device shown in FIG. 6 can be combined with one or the other of those shown in FIG. 7 or FIG. 9 i.e., the low-pressure stage of FIG. 6 may be constituted, for example, by the pump shown in FIG. 9. In this case, the hydraulic fluid compressed in the chamber 136, instead of being sent direct to the injector, serves to actuate the piston receiver 76 (FIG. 6) of the high-pressure stage, the stroke of this piston receiver being further reduced as the speed rises above the predetermined speed.

I claim:

1. In a device for controlling the quantity of liquid fuel fed from a source thereof to a means for injecting the fuel into an internal combustion engine which is responsive in speed to the quantity of fuel injected thereinto, the improvement comprising:

suction pump means including cylinder means and piston means;

said piston means being disposed within said cylinder means and being reciprocable therewithin;

driving means operative by said engine and engageable with said piston means to reciprocate the same within said cylinder means at a rate responsive to the speed of said engine; said piston means being reciprocable in one direction to define a suction stroke and being reciprocable in the opposite direction to define a pressure stroke;

said cylinder means having a fixed pressure face means;

that portion of said cylinder means between said pressure face means and the end of said piston means defining a chamber means, the volume of which increases during said suction stroke and decreases during said pressure stroke;

first conduit means establishing communication between said suction pump means and said source of fuel;

second conduit means establishing communication between said chamber means and said means for injecting the fuel into said engine; said first conduit means including spaced apart first and second passage means through said cylinder means;

said first passage means communicating with said chamber means during said piston means suction stroke to admit liquid fuel from said source thereof into said chamber means; means for blocking said first passage means during at least a part of said pressure stroke to interrupt the supply of said liquid fuel from said source thereof, whereupon said fuel already in said chamber means is forced under pressure into said second conduit means; hydraulic seal means formed between said piston means and said cylinder means to prevent said chamber means from communicating with the atmosphere;

said hydraulic seal means including a reduced diameter portion extending axially along said piston means between the ends thereof; said reduced diameter portion of said piston means and said surrounding cylinder means serving to define annular groove means;

said second passage means communicating with said annular groove means whereupon said annular groove means is filled with fuel from said source;

said annular groove means being elongated axially of said piston means for a length such that, regardless of the position of said piston means within said cylinder means, said annular groove means will still remain in communication with said second passage means;

said hydraulic seal means hence being in constant communication with said source of liquid fuel, whereby the liquid pressure within said annular groove means will remain substantially constant and will be substantially unaffected by pressure variations within said chamber means; and,

calibrated jet means operatively interposed in said first conduit means to limit the quantity of fuel passing therethrough to less than the capacity of said chamber means and more than the quantity of fuel to be fed to said means for injecting the fuel into the engine.

2. The improvement defined in claim 1 further including bypass means for establishing communication between said chamber means and said source of fuel, at least during the terminal portion of said pressure stroke, to permit fuel to bypass and to return to said source.

3. A device in accordance with claim 2 wherein said bypass means includes a third conduit means establishing communication between said chamber means and a receiver for bypassed fuel, bypass valve means operatively interposed in said third conduit means, and actuating means operatively interconnecting said bypass valve means with the engine to open said bypass valve means at least during the terminal portion of said pressure stroke of said piston means.

4. A device in accordance with claim 3 wherein said actuating means includes a cam means defining portions operatively connected to said bypass valve means to open the same during the initial and terminal portions of said pressure stroke of said piston means.

5. A device in accordance with claim 2 wherein said tcyclinder, said piston means including a large piston recylinder, said piston means including a large piston reciprocably carried in said large cylinder and a small piston reciprocably carried in said small cylinder, said chamber means including a large chamber defined by said 4 large cylinder and said large piston, and a small chamber defined by said small cylinder and said small piston.

6. A device in accordance with claim 5 wherein said large and small chambers are in communication with each other and with said first and second conduit means.

7, A device in accordance with claim 6 wherein said driving means includes a first driving member operatively interconnecting said large piston with the engine and a second driving member operatively interconnecting said small piston with the engine, said first and second driving members being synchronized to displace said small piston alone during a portion of said pressure stroke thereby feeding fuel to the means for injecting the same into the engine, and to displace said large and small pistons together during at least the terminal portion of said pressure stroke thereby bypassing fuel from said chamber means.

8. A device in accordance with claim 6 wherein said small cylinder is defined by portions of said large piston, said driving means including a driving member operatively interconnecting said small piston with the engine to displace said small piston alone during a portion of said pressure stroke thereby feeding fuel to the means for injecting the same into the engine, spaced portions of said driving member engaging said large piston during at least the terminal portion of said pressure stroke thereby bypassing fuel from said chamber means.

References Cited by the Examiner UNITED STATES PATENTS 1,752,386 4/1930 Mahler 123-139 1,926,743 9/1933 Hill.

1,952,154 3/ 1934 Atteslander.

1,974,851 9/1934 Hurst 10340 X 2,264,898 12/1941 Bovard.

2,270,127 1/1942 Kravits 10340 2,281,045 4/1942 Outin 123-139 3,071,074 1/1963 Bessiere 1032.1

0 MARK NEWMAN, Primary Examiner.

LAWRENCE M. GOODRIDGE, Examiner.

Claims

1. IN A DEVICE FOR CONTROLLING THE QUANTITY OF LIQUID FUEL FED FROM A SOURCE THEREOF TO A MEANS FOR INJECTING THE FUEL INTO AN INTERNAL COMBUSTION ENGINE WHICH IS RESPONSIVE IN SPEED TO THE QUANTITY OF FUEL INJECTED THEREINTO, THE IMPROVEMENT COMPRISING: SUCTION PUMP MEANS INCLUDING CYLINDER MEANS AND PISTON MEANS; SAID PISTON MEANS BEING DISPOSED WITHIN SAID CYLINDER MEANS AND BEING RECIPROCABLE THEREWITHIN; DRIVING MEANS OPERATIVE BY SAID ENGINE AND ENGAGEABLE WITH SAID PISTON MEANS TO RECIPROCABLE THE SAME WITHIN SAID CYLINDER MEANS AT A RATE RESPONSIVE TO THE SPEED OF SAID ENGINE; SAID PISTON MEANS BEING RECIPROCABLE IN ONE DIRECTION TO DEFINE A SUCTION STROKE AND BEING RECIPROCABLE IN THE OPPOSITE DIRECTION TO DEFINE A PRESSURE STROKE; SAID CYLINDER MEANS HAVING A FIXED PRESSURE FACE MEANS; THAT PORTION OF SAID CYLINDER MEANS BETWEEN SAID PRESSURE FACE MEANS AND THE END OF SAID PISTON MEANS DEFINING A CHAMBER MEANS, THE VOLUME OF WHICH INCREASES DURING SAID SUCTION STROKE AND DECREASES DURING SAID PRESSURE STROKE; FIRST CIRCUIT MEANS ESTABLISHING COMMUNICATION BETWEEN SAID SUCTION PUMP MEANS AND SAID SOURCE OF FUEL; SECOND CONDUIT MEANS ESTABLISHING COMMUNICATION BETWEEN SAID CHAMBER MEANS AND SAID MEANS FOR INJECTING THE FUEL INTO SAID ENGINE;